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Losing my mind


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Morning guys.

So a while back i posted about how even with solar we were still pulling 22kwh and still being a complete

newbie i started to switch off the eskom mains in the house and drain the batteries like people suggested.

I was under the assumption that the Axpert inverter did some magic and automatically disconnected Eskom

mains and would drain the batteries, as i have learned now, DONT MAKE ASSUMPTIONS!

 

Fast forward and  we just gut got a bill from city of JHB and we are now pulling down a 30khw!?

In the eve we switch off EVERYTHING at the mains except fridge and the electric fence, even the router gets shut down

when we sleep, in the eve after i shut everything off i see on the axpert a max of 15w draw and its all off the batteries.

So today i figured i would go take a look at the Eskom meter to see if maybe i can spot if there is any draw there.

Its a HXE310p and there im not entire sure how to properly read it.

 

So for interest sakes i switched on the pool pump and went to monitor the meter, i dont see anything that shows constant

draw of power.

To take it a step further i ended up switching off all the breaker switches on the Eskom board outside of the property where

the Eskom meter is, everything connected to the inverter was working like it should which is lights/plugs and all the stuff connected

to eskom such as geyser and pool pump were off  ,so at least i know the solar system is doing its job.

 

This leaves me with some thoughts.

1: Is the axpert pushing back to the eskom smart meter? *dont see how since the AC line to the board is shut down at the moment, Axpert is only seeing the panels*

2: Fault smart meter? *is it even possible*

3: Maybe someone is stealing power from me?

 

If you guys would like some pics of the setup/Eskom meter il be more than happy to take

 

Thanks guys

Edited by Launge
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4 hours ago, Launge said:

This leaves me with some thoughts.
1: Is the axpert pushing back to the eskom smart meter? *dont see how since the AC line to the board is shut down at the moment, Axpert is only seeing the panels*
2: Fault smart meter? *is it even possible*
3: Maybe someone is stealing power from me?

1: Not sure ... 
2: Yes.
3: Yes.
4: Their is a mix-up on Jhb accounts department. 

For 30 000kWh per day is a "helse" lot of power. We used to peak at 25kWh per month.

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Your problem is almost similar to mine.

What I have figured out so far is that when inverter starts to mix grid supply with either PV or battery, it does something strange to the grid supply that reduces the power factor at the inverter AC input significantly (<=0.5).  I have got to know this as I have 2 energy meters installed both at inverter AC input and output.  They measure Volts, Amps, Watts and KWh.  I have attached a picture of those energy meters.  The left one in the picture measures the AC input.  Check the PF on both left and right meters and see the difference.  At night, when PV stops working, the power factor gets normal (>=0.9).  If you don't know how to calculate ... you can do it by dividing the real power (Watts) by apparent power (volts x amps).

Can somebody on this forum shed some more light on to this?

20180916.jpg

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20 hours ago, Launge said:

 

This leaves me with some thoughts.

1: Is the axpert pushing back to the eskom smart meter? *dont see how since the AC line to the board is shut down at the moment, Axpert is only seeing the panels*

2: Fault smart meter? *is it even possible*

3: Maybe someone is stealing power from me?

  1. Highly unlikely and since the Axpert does not synch with Eskom if it were to push back into the grid you would likely have an over-voltage situation.
  2. A possibility
  3. This is South Africa:lol:.

Could I ask for you to post your Axpert setings.

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3 hours ago, Launge said:

Morning Chris, im still a white belt in terms of this stuff.

I do have a cable that can connect to the axpert, what software should i use to see the settings?

From there i can do screen caps for you

Hi Launge

White belt is where we all start. 

  1. Push the Enter key below the LCD on the inverter for 3 seconds You will now enter the setup menu
  2. You can scroll through the settings using the up down arrows.
  3. Write down (or get your partner to write down) program 1 to 31 (or 39 on some inverters). Some numbers are missing.
  4. press Esc key to return to the normal display screens.
  5. If there is no activity for ½ minute or so it switches back to normal display screen.
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7 hours ago, Nadeem Ahmed said:

What I have figured out so far is that when inverter starts to mix grid supply with either PV or battery, it does something strange to the grid supply that reduces the power factor at the inverter AC input significantly (<=0.5)

I don't think this is the case with the Axpert since it is not grid-interactive at all, but for Infinis and those that are grid-interactive, this is completely normal. The power factor is cos(theta), where theta is the phase angle between the voltage and current. The power is the so-called "vector product" or dot-product if you will between voltage and current, and if you've done any algebra somewhere in your career, that is (almost as you would expect) the euclidean magnitudes (or RMS value) of either multiplied by cos(theta).

Why bring this up? Well it means everything we know about dot products apply here. The magnitudes are by definition positive, so the only way to get the power to be negative is for cos(theta) to be negative, that is for theta to be in the range π/2 to 3π/2 (or 90° to 270°). If you are feeding the grid I would expect this to properly swing negative, but when you're playing balancing games, it tends to hover around zero.

This confuses the heck out of some people. They stick a clamp meter on it and see 2A flowing... yet there is no power. Well... because this is what the power factor is!

energy_meter.jpg.4dfc415777f991c82a68f5639fcea83f.jpg

Cos(theta) = 0.05. I'm not making this up :-)

Edited by plonkster
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OK guys sorry for the delays, been crazy busy but had some time off this morning

I've added some pics from powerwatch and the setup in general *which im sure will be deemed illegal in jHB come 2019*

Excuse the blurry battery bank pic, they're Trojans and i think my camera was drunk.

 

IMG_20180920_093512.jpg
IMG_20180920_093519.jpg
IMG_20180920_093526.jpg
IMG_20180920_093540.jpg

 

Edited by Launge
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On 2018/09/16 at 3:35 PM, plonkster said:

I don't think this is the case with the Axpert since it is not grid-interactive at all, but for Infinis and those that are grid-interactive, this is completely normal. The power factor is cos(theta), where theta is the phase angle between the voltage and current. The power is the so-called "vector product" or dot-product if you will between voltage and current, and if you've done any algebra somewhere in your career, that is (almost as you would expect) the euclidean magnitudes (or RMS value) of either multiplied by cos(theta).

Why bring this up? Well it means everything we know about dot products apply here. The magnitudes are by definition positive, so the only way to get the power to be negative is for cos(theta) to be negative, that is for theta to be in the range π/2 to 3π/2 (or 90° to 270°). If you are feeding the grid I would expect this to properly swing negative, but when you're playing balancing games, it tends to hover around zero.

This confuses the heck out of some people. They stick a clamp meter on it and see 2A flowing... yet there is no power. Well... because this is what the power factor is!

energy_meter.jpg.4dfc415777f991c82a68f5639fcea83f.jpg

Cos(theta) = 0.05. I'm not making this up :-)

May I ask why you refer to cos(theta). In normal house hold ... the VARs maybe from a fat pump but house holds are 90% resistivity and this should not have an impact. I could not see what type of meter he has but unless it is a 3 phase smart meter var has almost 0 impact. Will not be surprised if he feeds back in meter or the geyser warms at night which  is an issue. I am trying to understand your cos(theta). Liewer laat as nooit B)

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1 hour ago, Erastus said:

And at night?

Do you heat your geyser at night. If so, why?

I have one 150 litre geyser on a timer. I allow it to heat for 4  5 hours a day, but only if the thermostat say its time to heat. We are 3 adults and 4 children going through the bath or shower each evening, and in the mornings there is still enough hot water for each of the adults to take a shower again. Then at 10 in the morning the geyser switches on again and in the evening the cycle continues.  

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We have one geyser for upstairs which is run on eskom and one with evacuated tubes for downstairs. 

The one upstairs is never used and is always off at the db.

Geywise timer install also. 

Prior to having solar installed were we averaging 22kwh and both geysers were running off eskom back then. 

Now we're averaging 10kwh more while pretty much shutting off everything at night. Inverter shows a load of 18w to 20w when we shut down for the eve. 

So I the only thing I can think of is either something is wrong with this install, maybe we're feeding back into the grid or the meter must be faulty somehow. 

I want to make sure all is right in my side before I contact city of jhb. 

Also if there is someone knowledge ranburg side that can help please let me know. 

 

This is beyond frustrating at this point

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1 hour ago, Erastus said:

May I ask why you refer to cos(theta).

cos(theta) is the power factor, the "90% resistive" you speak of. I've also seen it referred to a cos(phi), using a different greek letter. It's exactly the same thing. The cosine of the phase angle IS the power factor :-)

An inverter that is feeding into the grid, especially one that is using a grid limiter, that is one that attempts to feed in exactly as much power as is used, creates a power vector that is equal but opposite to the power vector of the consumption. The result is that the combined phase angle is going to be perpendicular and you will get insanely low power factors when measured at the metering point.

I can't exactly remember what my point was about that though :-)

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22 minutes ago, plonkster said:

cos(theta) is the power factor, the "90% resistive" you speak of. I've also seen it referred to a cos(phi), using a different greek letter. It's exactly the same thing. The cosine of the phase angle IS the power factor :-)

An inverter that is feeding into the grid, especially one that is using a grid limiter, that is one that attempts to feed in exactly as much power as is used, creates a power vector that is equal but opposite to the power vector of the consumption. The result is that the combined phase angle is going to be perpendicular and you will get insanely low power factors when measured at the metering point.

I can't exactly remember what my point was about that though :-)

Tnx I understand. I thought this was not feeding into the grid. Only power factor is from air-con or swimming pool  small motors. In theory 0 shift  the "feeder" cables are short and cap in theory also 0.  Tnx

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